Product development of machines, including large, heavy earthmoving machines, often benefits from running virtual simulations of new designs before any prototypes or production machines are built. By evaluating the performance and durability of machine systems and components, such as, for example, the engine, structures, powertrain, and hydraulic implements using only a virtual model, designs can be optimized before any physical parts are actually constructed or assembled. It is important, however, that the simulation is operated in a way that is representative of human operators.
Traditional development of operator models has focused on rule-based logic or the use of proportional-integral-derivative (PID) controllers applied to a state machine. Simple rule-based models, however, are often brittle and become unsatisfactory when the design parameters of the machine or the boundary conditions of the simulation are changed. PID controllers require manual tuning and suffer sensitivity to the initial simulation parameters. As such, robust human-like trajectories are hard to achieve.
There are advanced control methods which are better suited for complicated behavior by imposing a more complex control structure on the flow of data. However, these advanced control methods require careful design and control theory expertise to tune them correctly. In some cases, they require complete knowledge of the system dynamics or do not guarantee transient learning behavior. Besides model complexities, some simulation scenarios are virtually impossible to control due to the chaotic system dynamics. Thus, using or creating operator models that mimic human behavior is difficult using conventional techniques.
U.S. Pat. No. 7,761,269 to Kraal et al. discusses a system for subjective evaluation of a vehicle design within a virtual environment. The system includes a scalable physical property representative of the vehicle design and a computer system for digitally creating a virtual environment having a virtual human immersed within. The system also includes a motion capture system for sensing a motion of an evaluator and communicating the sensed motion of the evaluator to the computer system and a virtual reality display mechanism for providing the evaluator a view of the virtual environment while evaluating the vehicle design.